Markup languages, such as the Standard Generalized Markup Language (SGML), Extensible Markup Language (XML), HyperText Markup Language (HTML), etc., are used to define how data is formatted and classified in electronic documents. SGML is the international standard for defining descriptions of the structure of different types of electronic documents. SGML is very large, powerful, and complex. It has been in heavy industrial and commercial use for many years, and there is a significant body of expertise and software to go with it. XML is a lightweight cut-down version of SGML, which keeps enough of its functionality to make it useful but removes all the optional features which make SGML too complex to program for in a Web environment. XML was designed to meet the requirements of large scale web content providers by providing an industry-specific vendor-neutral data exchange. HTML is a small application of SGML used on the Web. HTML defines a very simple class of report-style documents, with section headings, paragraphs, lists, tables, and illustrations, with a few informational and presentational items, and some hypertext and multimedia.
Originally designed to meet the challenges of large-scale electronic publishing, XML is also playing an increasingly important role in the exchange of a wide variety of data on the Web and elsewhere. As organizations continue to adopt XML as a standard for representing documents and transferring data, there is an increasing demand for a safe, efficient and reliable method for archiving this data. However, due to the architecture of XML this data type cannot be archived in the way that conventional data is stored using standard document archival processes. The reason for this is that there are multiple external items/resources which must be associated with an XML document. In order to truly archive and retrieve an XML document and retain fidelity of the document, all of the resources which are referenced within the XML document must either be archived or made available indefinitely on the web server so they can be referenced by the XML document.
An XML document is made up of a plurality of tags. Tags define the syntax for describing one or more elements of data, for example, <day>Monday</day> or <customer name>IBM</customer name>, wherein <day> and <customer name> are the tags that define the type of data enclosed within a start < > tag and a finish </> tag and “Monday” and “IBM” are the data elements.
An example of an XML document (EXAMPLE 1) is presented below. Shown in italics and underlined are the resources that are required in order to format and display the content of the XML document correctly.